Simplified -- How to Work around errata e2448 -- Part 2 Clock Code in RAM

eli_hughes — Sun, 30 Oct 2011 08:44:46 GMT

This is a follow up to some other posts about getting around errate e2448 (which should be posted everywhere and is extremely nasty!!)

about 9 months I got a solution from support that I posted that never really worked right.

I have a much simpler solution now. See Attached.

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A two step solution

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1.) At the *(.relocate_code) to the linker command file in the .app_data section right after *(.data). This will allow one to locate functions in the initialized data section (i.e. at startup stuff in this area is copied from init values in the flash.

.app_data: AT(___ROM_AT)

{

* (.sdata)

* (.data)

*(.relocate_code) <<<<<<<<

.= ALIGN(0x4) ;

*(.ARM.extab)

1.) .= ALIGN(0x4) ;

2.) A couple useful Macros:

#pragma define_section relocate_code ".relocate_code" ".relocate_code" ".relocate_code" far_abs RX

#define __relocate_code__ __declspec(relocate_code)

3.)Use the __relocate_code__ macro infront the function delclarations

_relocate_code__ void InitClock()

{

// If the internal load capacitors are being used, they should be selected

// before enabling the oscillator. Application specific. 16pF and 8pF selected

// in this example

OSC_CR = OSC_CR_SC16P_MASK | OSC_CR_SC8P_MASK;

// Enabling the oscillator for 8 MHz crystal

// RANGE=1, should be set to match the frequency of the crystal being used

// HGO=1, high gain is selected, provid

4.) Compile for FLASH and check the linker map. You will notice that there is a function of size 0xF2 in the .App_data section:

# .app_data

1FFF8000 0000000F .data @67 (main.obj)

1FFF800F 00000001 .data @400 (libc_Thumb_LE_v7M.a printformat_.o )

1FFF8010 000000F2 .relocate_code InitClock (Clock.obj)

I just tested this with the K40 tower board.

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One less step

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Also note that you should be able to change the

#pragma define_section relocate_code ".relocate_code" ".relocate_code" ".relocate_code" far_abs RX

#pragma define_section relocate_code ".data" ".data" ".data" far_abs RX

And not have to change the linker file. This makes it possible to relocate code without a special linker file.

-Eli

topic Simplified -- How to Work around errata e2448 -- Part 2 Clock Code in RAM in Kinetis Microcontrollers

Simplified -- How to Work around errata e2448 -- Part 2 Clock Code in RAM